Remember, it takes an EE (green or blue) mated to a dark brown (Maran or Welsummer) to create Olive Egger...

color is irrelevent... It just happens that most are barred, or black as that's the color of the two most commonly used anscestors-- the Marans.

It also doesn't help that barred on the female side is sex linked...

You could mate any hen in the world to a dark brown laying roo-- and expect any color offspring... but I would expect that unless that roo is something other than a black or cockoo then color will not arise.. if not, then there's a great chance that the black and cockoo will be dominate over the colored, unless it's pure white.